RS-232 is a standard for serial communication that defines how data is transmitted between devices, such as computers and modems. It uses a set of electrical signals and voltage levels to represent binary data, allowing for the exchange of information over short distances, typically up to 50 feet. This standard specifies the physical and electrical characteristics of the connection, including pin configurations and signal timing. Although it has been largely replaced by newer technologies like USB and Ethernet, RS-232 remains important in various industrial and legacy systems for its simplicity and reliability.